Bromophenol isomerization

ABSTRACT

A process for enriching the ortho bromo isomer content of a phenolic material characterized by the presence of at least one brominated phenol and a bromine content of less than two atoms of bromine for each of phenolic nucleus. The phenolic material may particularly consist of at least one monobrominated and/or dibrominated product of a compound of the formula: WHEREIN R1, R2 and R3 are hydrogen or primary or secondary alkyl groups containing one to four carbon atoms. The process is characterized by isomerization and/or disproportionation of the starting material in the presence of hydrogen bromide and an inert solvent, (such as a chlorinated hydrocarbon or a nitro aromatic hydrocarbon), at a temperature in the range -25* to 60* C. for a period of time sufficient to obtain a high concentration of the desired ortho bromo isomer. The isomerization of the bromination products of m-cresol to obtain 6-bromo-m-cresol is particularly described.

United States Patent OBara 51 Aug. 1,1972

( BROMOPHENOL ISOMERIZATION Edward John OBara, Manville, NJ.

American Cyanamid Company, Stamford, Conn.

22 Filed: April 25,1968

21 Appl.No.: 724,282

[72] Inventor:

[73] Assignee:

[52] US. Cl. ..260/623 R, 260/623 H [51] Int. Cl ..C07c 39/26 [58] Fieldof Search ..260/623, 623 H, 623 R [5 6] References Cited UNITED STATESPATENTS 8/1955 Dietzler ..260/623 3,293,309 12/1966 Zembra ..260/6233,449,443 6/1969 Dietzler ..260/623 FOREIGN PATENTS OR APPLICATIONS784,782 5/1968 Canada ..260/623 Primary ExaminerBernard Helfin AssistantExaminer-W. B. Lone Attorney-Theodore C. Virgil [57] ABSTRACT A processfor enriching the ortho bromo isomer content of a phenolic materialcharacterized by the presence of at least one brominated phenol and abromine content of less than two atoms of bromine for each of phenolicnucleus. The phenolic material may particularly consist of at least onemonobrominated and/0r dibrominated product of a compound of the formula:

10 Claims, N0 Drawings BROMOPHENOL ISOMERIZA'I'ION This inventionrelates to the preparation of phenolic compounds having a bromosubstituent in a position ortho to the hydroxyl group from otherbrominated phenolic materials.

Bromination of phenolic compounds in which the para position and atleast one ortho position are unsubstituted, usually produces abromination product rich in the para-bromoisomer. Thus, it is diflicultto obtain an ortho-bromo isomer from these starting materials by anydirect practical bromination procedures presently known. This is true,for example, in the bromination of m-cresol, the variousmeta-substituted xylenols, and other lower alkyl substituted phenols.For this reason the ortho isomers are relatively expensive and notreadily available as intermediates in the manufacture of known products.

One method for obtaining the desired ortho-isomers is to form abromination product by conventional means, and convert the brominatedmaterials to the desired ortho-isomers. One method of producingortho-isomers "indirectly" is disclosed in US. Pat. No. 3,293,309.Therein it is said that 2-bromophenol, 6- bromo-o-cresol andfi-bromo-m-cresol are obtained from the corresponding 4-bromo-isomer byheating the latter at a temperature from l to 200 C. in the presence ofan acidic catalyst for a period of time suffrcient for a substantialdegree of isomerization to take place. The acidic catalyst is thehydrogen bromide generated in the bromination step or a Friedel craftscatalyst such as AlCl AlBr,, FeCl and the like, or a combination of twoor more of these. Best results are reported with a combination ofhydrogen bromide and a non-volatile co-catalyst, preferably phosphoricacid. The difficulty with this process is that isomerization is carriedout at high temperatures which results in a relatively highconcentration of dibrominated and decomposition products. Moreover, inthe case of m-alltylphenols, e.g., m-cresol, the isomerization leads toalmost equal amounts of the 2-bromo and 6-bromo isomers. Although bothisomers are ortho bromo substituted, it is usually desirable to obtainone or the other of these isomers in predominant amounts. The process ofthe prior art is not satisfactory in such cases. The process is alsodisadvantageous from the standpoint of the need to handle highlycorrosive hot hydrogen bromide.

it is an object of the present invention to provide a new process forthe preparation of ortho brorno phenols from other brominated phenolicmaterials containing at least one phenolic compound in which at leastone ortho position is unsubstituted. it is a further object of theinvention to provide a process for the enrichment of a brominatedm-cresol starting material with respect to the 6-bromo-cresol contentthereof.

In accordance with the present invention, it has been discovered thatbrominated phenolic compounds containing at least one unsubstitutedposition ortho to the phenolic hydroxyl group can be isomerized to thedesired ortho bromo isomer in good yields by allowing the para bromoisomer to "age" at a relatively low temperature in the presence of aninert solvent and hydrogen bromide for a limited period of time. In afurther aspect of this invention an unbrominated phenolic material isbrominated in the presence of the solvent which is useful during theisomerization and/or disproportionation of the brominated phenolicproduct to the desired ortho-isomer-rich product.

The process of this invention is distinguished by the fact that thedesired conversion (i.e., isomerization and/or disproportionation), andpreferably, also the bromination, is conducted in the presence of aninert solvent at relatively low temperatures for a period of time whichis sufficient to obtain a high concentration of the desired ortho bromoisomer. in most cases this occurs at equilibrium. However, it is afurther distinction of the invention that the maximum concentration of6-bromo-m-allrylphenols, e.g., o-bromo-m-cresol, has been found to occurat a timer prior to equilibrium.

One of the essential features of the process of this invention is theuse of an inert solvent in the conversion reaction, and preferably alsoin the bromination reaction. The solvent permits the attainment of themaximum concentration of the desired ortho isomer in the shortest timeat the lowest temperature. In the absence of a solvent the conversion tothe ortho isomer occurs, but at a very slow and impractical rate at lowtemperatures.

The solvents of choice are the chlorinated aliphatic and aromatichydrocarbons and nitro aromatic hydrocarbons. Chlorofonn is preferredfor most substrates. Other suitable solvents include chlorinatedbenzenes, chlorobenzene, carbon tetrachloride, methylene chloride,tetrachloroethylene, nitrobenzene, and combinations of two or more ofthese sol vents. The amount of solvent used in the reaction mixture canbe optimally that amount which will result in a high yield of thedesired ortho isomer in a desirably short time at about roomtemperature. In general, this will be at least one part of solvent foreach part by weight of the brominated phenolic starting material, andpreferably from about 5 to about 10 parts per part of brominatedphenolic starting material, on the same basis.

It has been found that much of the hydrogen bromide generated in thebromination reaction remains in solution and this amount is sufficientto catalyze the conversion to the desired ortho isomers at thetemperature envisioned for the process. Although, not necessary to thesuccess of the conversion, additional HBr may be bubbled through thereaction mixture during the interval in which conversion occurs, tomaintain a saturated solution of HBr. This latter technique may bedesirable when the isomerization and/or disproportionation reaction isconducted at the upper temperatures of the range described below sinceunder these conditions the volatile HBr tends to leave the reactionmixture.

One of the surprising aspects of the process of this invention is thatconversion to the ortho isomers occurs and proceeds at a reasonable rateeven at low temperatures. Useful results are obtained in the broad rangeof from about -25 to about C. it is preferred to conduct theisomerization at a temperature in the range of from about 25 to about 60C., and still more preferably at a temperature in the range of fromabout 20 to about 30 C.

The present invention is applicable to brominated derivatives of thephenolic compounds of the formula l wherein R,, R, and R, are hydrogenor primary or secondary alkyl groups (one to four carbon atoms).Included among the phenolic compounds described by the above formula arephenol, ortho-cresol, metacresol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol,ortho ethylphenol, meta ethylphenol, ortho propylphenol, orthoisopropylphenol, ortho butylphenol, ortho isobutylphenol, metapropylphenol, meta isopropylphenol, meta butylphenol, betaisobutylphenol, 2,5- diethylphenol, 2,3-diethylphenol,3,5-diethylphenol, and the like.

The ortho-bromo phenols which are prepared by the process of thisinvention are phenols with a free paraposition, one bromine atom on theposition ortho to the phenolic hydroxyl group and, up to three primaryor secondary alkyl substituents. The brominated phenolic startingmaterials which are useful in the process of the invention may containonly a single phenolic com pound or it may be a mixture of unbrominated,monobromo and/or dibrominated phenolic com pounds. The mixtures ofphenolic materials can be obtained by simply mixing a brominated phenolwith one or more brominated and/or unbrominated phenols, or, moreusually, by direct bromination of an unbrominated phenolic material.Depending upon bromination conditions, the bromination mixture cancontain a variety of compounds ranging from unbrominated startingmaterial to dibrominated compounds and including various partandorthomonobrominated phenolic materials. Bromination should not beallowed to proceed beyond the point at which two equivalents of brominehave reacted with each equivalent of the phenolic compound. ln general,in fact, if the bromination is being conducted for the purpose ofproducing starting materials for the process of this invention, it isdesirable to brominate to the point where between 0.5 and 1.5, andpreferably 1 to 1.3, equivalents of bromine per phenolic equivalent arereacted. This will mean that in the reaction product there is only asmall amount of unreacted starting material, a minor amount ofdibromo-phenolic materisis and a preponderance of mono-brominatedmaterial. Such mixtures are eminently suitable for the purposes of thisinvention.

As has been noted hereinabove, the sources of the brominated phenolicmaterial is not important. Pure materials can be blended to givesimilated bromination mixtures or mixtures of brominated derivatives canbe formed in situ. For example, it is possible to blend a predominantlydibrominated phenol, with an essentially unbrominated phenol, and, bydisproportionation, obtain a mixture which has a desirably high ratio ofmono-brominated materials.

When the phenolic compounds of formula I are brominated, the bromineatom is directed predominantly to the para position. in the case ofm-cresol, e.g., the concentration of the isomer in the reaction mixturefollowing completion of bromination in the absence of solvent is in theorder of about 50-55 mole percent, while the concentration of the 2- ando-isomers totals about 30 mole percent. The same mixtures, after agingto attain essentially equilibrium conditions, contains about 20 molepercent of each of the 2- and 6-isomers and 26 mole percent of thed-isomer. Though not previously recognized, the concentration of the6-bromo isomer is greater at an intermediate time after bromina- 4 tion,but before equilibrium of the bromination mixture has been achieved.

lt has been found that the isomerization of the para bromo phenolsproceeds to the equilibrium state in a relatively short time when thereaction is conducted according to this invention. The maximumconcentration oftheorthobrormisomerisnormallyattainedat equilibrium.However, it has been discovered that the isomeriration of4-bromo-m-cresol proceeds to equilibrium through an intermediate maximumconcentration of the o-bromo n-cresol. At equilibrium the 2- andfi-isorners are present in approximately equal concentrations. Thisintermediate maximum concentration represents about 38 percent of the6-bromo-mcresol after 48 hours at 25" C. when the isomerization isconducted in a solvent consisting of 4 parts of chlorobenaene and onepart of carbon tetrachloride. The equilibrium concentration is about 20percent.

The bromination reaction is conducted under conventional conditions,preferably using at least a stoichiometric amount of bromine. Whenstoichiometric quantities of bromine are used, the reaction mixture willusually contain some unreacted phenolic material. For example, whenbromo-m-cresol reaction mixture is allowed to stand in the presence ofHBr, some of the mono-brominated product is debrominated to m-cresol andbromine. As a result there is an increase in concentration of dibromoisomers (2,4-, 2,6- and 4,6-) by reaction of the bromine with themonobrominated product. Thus, when the desired quantity of the orthoisomer is attained, additional bromine may be added to the reactionmixture to brominate the remaining unbrominated cresol prior toseparation of the product.

As noted above, it has also been discovered in accordance with thisinvention that dibrominated products resulting from the bromination ofthe phenolic compounds of this invention, specifically the 2,4- and 4,6iibromo-m-alkylphenols can be converted to the corresponding ortho bromoisomer by disproportionau'on of a mixture of the dibromo compounds withan unbrominated phenolic compound, preferably an equimolar quantity ofthe corresponding unbrorninated phenolic compound, in the presence ofl-lBr. Thus a mixture of m-cresol and 2,4-, and 4,6-dibrorno-mcresolscan be disproportionated, resulting in the formation of the desired2-bromo and fi-bromo-m-cresols.

When the maximum amount of the desired isomer has been obtained, thereaction mixture is drowned in an alkaline medium, e.g., aqueous sodiumhydroxide. The aqueous layer containing the phenolic compounds iswithdrawn and neutralized with an acid. The product portion is thenseparated and distilled in vacuo to obtain the ortho bromo isomers. Inthe case of m-cresol the 2- and 6-bromo isomers have similar boilingpoints, and are not easily separated by distillation; they may beseparated by forming the benzene or paratoluene-sulfonates, separatingthe sulfonates by crystallization,

recrystallin'ng and finally hydrolyzing the sulfonate to the desiredbrominated phenolic compound. Other suitable isolation techniques can beused.

The following examples are presented to further illustrate thisinvention. in all the examples where pertinent vapor phasechromatographic data are given, the following system was used unlessotherwise noted.

Colurrm: 6 a. 20 percent Carbowax 20M Bit;

Chromosorb W; 60/80 mesh Detector: Thermal conductivity Carrier gas:Helium Flow rate: 200 mlJmin. Temperature: Injection port-200 C.;Block-255 C. Column:

a) 135 C. for separation of 2-bromo-m-cresol, 6-

bromo-m-cresol and m-cresol. b) ,l75-200 C. for separation ofdibromo-mcresols and 4-bromo-m-cresol from the above. Samples weretreated with sodium carbonate prior to 4,6-dibmmom- 10.0 ".5 I69 creaoldibromo (2.4+ 4.6) m-cresol 7.5 9.8 l4.5 others l.9

This example illustrates (a) that the concentration of the 6-isornerdoes not significantly change in the process whereu the concentration ofthe 2-isorner is more than doubled, (b) that the state achieved in step(3) is approximately the equilibrium condition, and (c) that the optimumconcentration of the 6-isomer is not waned "alas agsanwsefwse mesanalysis. Peak areas were calculated by the method of [5 triangles andgave mole percent directly.

EXAMPLE i Bromination and Isomerization of m-Cresol Without Solventm-Cresol was brorninated according to the procedure of Example 8 of U.S.Pat. No. 3,293,309.

m-Cresoi was brominated at 55"-65 C. with an equivalent of bromine addedas a gas carried by a stream of nitrogen. The reaction mixture was thenheated to l45-l55 C. for 6 hours in the presence of residual hydrogenbromide to determine the extent of isomerilation- The ix i awaat saltsts a EXAMPLE 2 Bromination of m-Cresol TABLE II.BROMINATION OF m-CREBOLVariation of composition with time (mole percent) Time (hrs) m-Cresol2-bromo fl-bromo 2- 6- Di-bromo 4-brorno 0 0 0 0 0. l5 4. 1 4. 7 28. 2Bromination l. 0 9. i 4. 4 48. 0 l. 6 l6. 0 0. 4 00. 0 2. 0 22. 0 l9. 258. B 0 22. 0 ii]. 2 68. B l 26. 6 20. ll 48. 2 8 84. 6 24. 2 34.11Isomorisation 6 37. 4 24. 8 81. 5 8 42. 2 23. l 27. (l 22 47. 8 22. 22i. 2 140 30. 9 3i. 2 l7. 7 206 40. 8 28. 0 l8. 8

tional 6 hours at the same temperature alter addition of l percent byweight of phosphoric acid and with a it is clear from the data thattheconcentration of the 6-isomer increases from 18.8 mole percent of thereacstream of hydrogen bromide bubbling through the tion mixture altercompletion of the brornination, to a liquid. The composition in terms ofmole percentages of the isomers (1) after the brornination, (2) alterthe first period of heating and (3) after the addition of phosphoricacid and the second period of heating the mixture saturated withhydrogen bromide, are listed below. Vapor phase chromatographic (VPC)analysis of the reaction mixture was compared with the analysis reportedin Example 8 of the above cited patent.

maximum of 30.2 mole percent after allowing the reaction mixture tostand at 25 C. for 8 hours in the presence of residual hydrogen bromide.Continued isomerization under the same conditions results in a reductionof the 6-isomer content, the entire mixture approaching the equilibriumstate. The maximum concentration of the 2-isomer occurs at equilibrium.

Hydrogen bromide was bubbled through a crude mixture of brorno-m-cresolat 0-5 C. for five minutes. The ice bath was removed and the mixtureallowed to warm to room temperature in a stoppered flask. The mixturesolidified and was allowed to stand at room temperature for 6 hours andthen heated on a steam bath in vacuo to liquify the solid and removel-iBr. The liquid was again saturated with l-lBr and allowed to lstandatroomtempersmreforatotalof96hours. EXAMPLEG ru'mAnalysisofthemixturesbyvaporphasechromtography showed the following(Tabb m lsomenzation Of 4-Bromo-3,5-D1methylphenol4-Bro1no-3,5-dimethylphenol (5.43 g., .027 mole) ADI-Em 5 was dissolvedin 44 ml. of chloroform. This solutionwassamrstedwithanhydroul-mrandallowedtostand at 25C. inastopperedflask.Samples were removed M periodically flor VPC analysis. Aging Tlms Lb-isomsr ni-crssol dlbromo M01 lo 3.5-61- 0 222 14 16s :91 Time PM: M liild diltthlph r l y Alter 6 hours 22.9 3.0 16.9 51.1 After 96 116m 26.!12.0 24.1 36.6

. 1 2.4- 2,6- 0 0.4 90.4 1.2 This example illustrates the slow rate ofincrease 1n rm.. 6.: a.s 20.9 8-2 0.5 1.5 63.7 11.9 10.: traceortho-isomer content when the 1somer1zation 1s con- 1 w 1 55 9.6 ductedin the absence 0! solvent at a low temperature. 4 9.1 64.3 15.1 9.9 0.524 10.2 64.1 14.1 8.6 2.2 411 10.1 61.9 16.0 8.3 3.1 12 10.9 51.2 11.29. 5.1 EXAMPLE 4 Brominlfion Ofm-Cwwl Colummflt. 10s tic-was (sumrubber) Column temperature: l$0-200C.,propsmmsd st6 permin m-Cresol (20g., 0.185 mole) was dissolved in a mixture of 80 ml. of chlorobenzeneand 20 ml. of carbon tetrachloride. To this solution was added asolution of Thi ex l inmates the applicability of the r m n (2 3-.13-135 m in 80 procea of the invention to other phenolic compoundschlorobenzene and 20 ml. of carbon tetrachloride over wherein thepredominating 4-bromo isomer is isome- 6 hours at 25 C. The solution wasthen allowed to rizedtothedesiredorthoisomer.

stand at 25 C. in a stoppered flask and samples were removedperiodically for VPC analysis with the follow- EXAMPLE 7 Helium low ms:45 mL/Inln.

mg results (Table Iv): Isomerization of 4-Bromo-m-Cresol in Nitrobenzene4-Bromo-m-cresol (5.0 3., 0.207 mole) was dissolved TABLE IV in 23 ml.of nitrobensene. The solution was saturated with anhydrous l-lBr andallowed to stand at 25 C. in a stoppered flask. Samples were removedperiodically for mole I; we l r s m-cresol Z-Br dlbromo 4a:

0 5.9 3.6 16-! 2-0 71- Time, Z-bmmo 6-l1rornodibmrno- 4-brorno- 16 8.28.8 33.4 4.1 45.4 hr. m-crasol m-crusol rn-cresol rn-cresol 24 11.6 9.836.7 4.5 40.4 411 9.1 12.11 311.2 5.5 34.4 66 10.0 14.2 ss.2 6.0 31.5 oo o 0 o 100 1311 10.5 11.1 36.3 1.6 28.6 4 (1) s s 119 24 2 13 6 6 13 9611 20 10 10 52 144 (210' 12 12 49 1:: 11:1: 1:" 1: 1: EXAMPLE 5 y 360 1114 16 16 44 624 12 1:4 16 16 43 lsomerization of p-Bromophenol withHydrogen 50 Bromide p-Bromophenol (4.63 grams, 0.027 mole) was dis 'mnmwsolved in 23 ml. of chloroform. The solution was saturated withanhydrous H81 and allowed to stand at 25 m8 empk the apphcablhty of theprocess of the invention in solvents other than C. inastoppered flask.Samples were analyzed by VPC. chlorinat ed y drocarbomdn panic "1m,nitmbemne o-bromo Dibromop-Bmrno- Ex A bdPLE 8 Time, hrs. Phenol Phenolphenols phenol Conversion of a Mixture of Dibrorno-m-Cresols and m- 0 o0 0 Cresol 20 6 6 6s 4a: 44 6 s 42 A solut1on of 5 g. of m-cresol 1n 20ml. of chloroform 10:: 49 1 10 34 was treated with two equivalents ofbromine in 20 ml. of chloroform over a period of 1 hour at 25 C. To this65 mixture was then added 5 grams of m-cresol in 10 ml. This exampleillustrates the applicability of the f hl f d th i t ll d t stand i aprocess of the invention to phenolic compounds which gtoppergd fla k at25 C, Sa l f VPC l i do not contain a mcta-alkyl group. were taken (A)alter brornination, (B) after adding m- 9 crmol, and (C) periodicallyduringthe isomenzation.

T e, 2,4- and 4,6- hrs. Z-bromo 6brorno m-cresol dibmmo d-bromo (A) (2)90 s (B) 49 46 5 3.5 (6) 41 4s 5 93 I5 (32) I7 26 23 I9 'Parenthetioalvalues refer to sum of Z-bromo and 6-bromo isomers.

This example illustrates the applicability of the process of theinvention to disproportionated dibrominated-m-cresols/m-cresol mixtureswith the resultant preparation of the ortho bromo isomers.

lclaim:

1. A process for preparing ortho-substituted bromophenols comprisingaging a solution of a brominated phenol, wherein the phenol prior tobromination has the formula;

wherein R,, R, and R, are hydrogen or primary or secondary alkyl groupsof l to 4 carbon atoms; wherein the said aging of said bro-minatedphenol is performed by aging a solution of the said brominated phenolwith hydrogen bromide in an inert solvent at a temperature in the rangeof 25C. to about 60C to increase the ortho bromo phenolic concentration.

2. A process as defined in claim 1 wherein said solution is in an inertsolvent selected from the group consisting of chlorinated hydrocarbonsand nitrobenzene.

brornophenols comprising brominating a phenol of the formula:

wherein R R and R, are hydrogen or primary or secondary alkyl groups ofl to 4 carbon atoms, aging a solution in inert solvent of the resultantbromination products with hy-drogen bromide at a temperature in therange of about 25C. to about C. to increase the proportion ofortho-substi-tuted bromophenols therein, stopping the aging step byadd-ing to said solution a basic material to react with the hy-drogenbromide in said solution, and separating the desired orthosubstitutedbrornophenol therefrom.

7. A process as defined in claim 6 wherein said bromination step andsaid aging step are both per formed in solution in the same inertsolvent.

8. A process as defined in claim 7 wherein said inert solvent is achlorinated hydrocarbon.

9. A process as defined in claim 8 wherein said phenol is m-cresol,xylene], or phenol.

10. A process as defined in claim 8 wherein said phenol is rn-cresol andwherein 6-bromo-m-cresol is separated in the last step thereof.

I i i i i Case 22, 401 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. '5 68] }67 Dated August 1 1G7? lnv n fl EdwardJohn O 'Bara It: is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

C01. 2, line 15, "timer should read time Col. 3, line 50, "part-'1should read para- Col. 7, line 39, insert as a heading over the fourthcolumn in Table IV "-Br";

C01. 8, line 54, "0.207' should read 0.027

Signed and sealed this 20th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

ROBERT GOT Attesting Offi TSCHALK Comissioner of Patents RM PO-wSD(10-69) uscouM-Dc eons-Poo I IL. GOVIINUIII 'IIIYIIG OFFICE I,"0-856-38!

2. A process as defined in claim 1 wherein said solution is in an inertsolvent selected from the group con-sisting of chlorinated hydrocarbonsand nitrobenzene.
 3. A process as defined in claim 1 including theadditional step of stopping the aging step by adding to said solution abasic material to react with the hydrogen bromide in said solution.
 4. Aprocess as defined in claim 3 including the further step of separatingthe desired ortho-substituted bromophenol from the mixture of productsthus obtained.
 5. A process as defined in claim 1 wherein said phenol ism-cresol, xylenol, or phenol.
 6. A process for preparingortho-substituted bromophenols comprising brominating a phenol of theformula: wherein R1, R2, and R3 are hydrogen or primary or secondaryalkyl groups of 1 to 4 carbon atoms, aging a solution in inert solventof the resultant bromination products with hy-drogen bromide at atemperature in the range of about -25*C. to about 60*C. to increase theproportion of ortho-substi-tuted bromophenols therein, stopping theaging step by add-ing to said solution a basic material to react withthe hy-drogen bromide in said solution, and separating the desiredortho-substituted bromophenol therefrom.
 7. A process as defined inclaim 6 wherein said bromination step and said aging step are bothperformed in solution in the same inert solvent.
 8. A process as definedin claim 7 wherein said inert solvent is a chlorinated hydrocarbon.
 9. Aprocess as defined in claim 8 wherein said phenol is m-cresol, xylenol,or phenol.
 10. A process as defined in claim 8 wherein said phenol ism-cresol and wherein 6-bromo-m-cresol is separated in the last stepthereof.